The purpose of an air drier, which preferably but not exclusively can be used on vehicles, is to remove moisture from the air delivered by the compressor before it reaches different air consuming devices. In an air drier of the two-tower type one tower is used to dry the air by a desiccant therein, while at the same time the other tower is regenerated by a small fraction of the dry air passed through the desiccant therein and to the atmosphere.
The valve mentioned above, which can be defined as an inlet valve and is of flip-flop type, directs the air to either one of the two drying towers and is governed by the pressure difference between its two outlets and also by the air flow itself. The pressure difference in turn is accomplished by other means in the air drier. A return force for the valve body to a neutral position is provided by spring means.